Computer Science. The English Language Perspective - Беликова (1176925), страница 15
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The interpreter program acts as a software simulation ofa machine whose fetch-execute cycle deals with highlevel language program statements rather than machineinstructions.9. Pure interpretation has the advantage of allowing easyimplementation of many source-level debuggingoperations, because all run-time error messages canrefer to source-level units.882. Answer the following questions:1. What are the criteria to evaluate the programminglanguages?2. Why is readability an important measure of the qualityof programming languages?3. Can the writabilities of different languages be different?Why?4.
What can influence the cost of a programminglanguage?5. What is the difference between the implementationmethods?3. Translate into English:Интерпретаторпрограммаилиустройство,осуществляющеепооператорнуютрансляциюивыполнение исходной программы. В отличие откомпилятора, интерпретатор не порождает на выходепрограмму на машинном языке. Распознав командуисходного языка, он тут же выполняет ее.
Как вкомпиляторах, так и в интерпретаторах используютсяодинаковые методы анализа исходного текста программы.Но интерпретатор позволяет начать обработку данныхпосле написания даже одной команды. Это делает процессразработки и отладки программ более гибким. Кроме того,отсутствие выходного машинного кода позволяет не«захламлять» внешние устройства дополнительнымифайлами, а сам интерпретатор можно достаточно легкоадаптировать к любым машинным архитектурам,разработавеготолькоодинразнаширокораспространенном языке программирования. Поэтомуинтерпретируемые языки, типа Java Script, VB Script,получилиширокоераспространение.Недостаткоминтерпретаторов является низкая скорость выполненияпрограмм.Обычноинтерпретируемыепрограммы89выполняются в 50-100 разнаписанных в машинных кодах.медленнеепрограмм,4.
Give the summary of the text using the key terms.Topics for essays (you might need additional information):Programming Languages Categorization.The Diversity in Programming Languages Application.Language Evaluation CriteriaComparative Analysis of Two Programming LanguagesBelonging to Two Different Categories90OPERATING SYSTEMSRead the following words and word combinations and usethem for understanding and translation of the text:application software - прикладное программноеобеспечениеsystem software - системное программное обеспечениеcore - ядро, цеитр, сущностьto accomplish - выполнять, достигатьhandheld - портативный, переноснойbooting - загрузкаdual-boot system - система с двойной загрузкойkernel - ядроshell - оболочкаin between - между, посерединеto swap - обменивать,to amount to - составлять, равнятьсяtime-sharing - разделение времениoffshoot - ответвлениеto recapitulate -резюмироватьto debug - отлаживатьcommand-line - командная строкаto tuck away - спрятатьsophistication - сложность, изощренностьModern software can be divided into two categories,application software and system software, reflecting thisseparation of goals.
Application software is written to addressour specific needs - to solve problems in the real world. Wordprocessing program, games, inventory control systems,automobile diagnostic programs are all application software.System software manages a computer system at a fundamentallevel.
It provides the tools and an environment in whichapplication software can be created and run. System software91often interacts directly with the hardware and provides morefunctionality than the hardware itself does.The operating system of a computer is the core of its systemsoftware. An operating system manages computer resources,such as memory, input/output devices, and provides aninterface through which a human can interact with thecomputer. An amazing aspect of operating systems is howvaried they are in accomplishing these tasks. Mainframeoperating systems are designed primarily to optimizeutilization of hardware.
Personal computer (PC) operatingsystems support complex games, business applications, andeverything in between. Operating systems for handheldcomputers are designed to provide an environment in which auser can easily interface with the computer to executeprograms. Thus, some operating systems are designed to beconvenient, others to be efficient, and others are somecombination of the two.A computer generally has one operating system that becomesactive and takes control when the system is turned on.Computer hardware is wired to initially load a small set ofsystem instructions stored in permanent memory (ROM). Theseinstructions load a larger portion of system software fromsecondary memory, usually a magnetic disk. Eventually all keyelements of the operating system software are loaded, start-upprograms are executed, the user interface is provided, and thesystem is ready for use.
This activity is often called booting thecomputer. The term boot comes from the idea of “pullingyourself up by your own bootstraps,” which is essentially whata computer does when it is turned on.A computer could have two or more operating systems fromwhich the user chooses when the computer is turned on. Theconfiguration is often called a dual-boot or multi-boot system.Note that only one operating system is in control of thecomputer at a given time.92DEVELOPMENTThe earliest computers were started with rudimentary “loader”program that could be used to configure the system to run themain application program. Gradually a more sophisticated wayto schedule and load programs, link programs together, andassign system resources to them was developed.As systems were developed that could run more than oneprogram at a time, the duties of the operating systems becamemore complex.
Programs had to be assigned individualportions of memory and prevented from accidentallyoverwriting another program’s memory area. A techniquecalled virtual memory was developed to enable a disk drive to betreated as an extension of the main memory, with data“swapped” to and from the disk as necessary. This enabled thecomputer to run more and/or larger applications. Theoperating system, too, became larger, amounting to millions ofbytes worth of code.During the 1960s, time sharing became popular particularly onnew smaller machines such as the DEC PDP series, allowingmultiple users to run programs and otherwise interact with thesame computer.
Operating systems such as MULTICS and itshighly successful offshoot UNIX developed ways to assignsecurity levels to files access levels to users. The UNIXarchitecture featured a relatively small kernel that providesessential process control, memory management, and file systemservices, while drivers performed the necessary low-levelcontrol of devices and a shell provided user control.Starting in the late 1970s, the development of personalcomputers recapitulated in many ways the earlier evolution ofoperating systems in the mainframe world.
Earlymicrocomputers had a program loader in read-only memory(ROM) and often rudimentary facilities for entering, running,and debugging assembly language programs.During the 1980s, more complete operating systems appearedin the form of Apple DOS, CP/M, and MS-DOS for IBM PCs.These operating systems provided such facilities as a file system93for floppy or hard disk and a command-line interface forrunning programs or system utilities. These systems could runonly one program at a time (although exploiting a little-knownfeature of MS-DOS allowed additional small programs to betucked away in memory).As PC memory increased from 640 KB to multiple megabytes,operating systems became more powerful.
Apple Macintoshoperating system and Microsoft Windows could managemultiple tasks. Today PC operating systems are comparable insophistication and capability to those used on mainframes.An interesting development that began in the mid-1980s is thegrowth of networks of personal computers running networkoperating systems and distributed operating systems. Networkoperating systems are not fundamentally different from singleprocessor operating systems. They obviously need a networkinterface controller and some low-level software to drive it, aswell as programs to achieve remote login and remote fileaccess. But these additions do not change the essential structureof the operating system.A distributed operating system, in contrast, is one that appearsto its users as a traditional uniprocessor system, even though itis actually composed of multiple processors.
Distributedsystems often allow applications to run on several processors atthe same time, thus requiring more complex processorscheduling algorithms in order to optimize the amount ofparallelism.Notes:DEC PDP - Digital Equipment Corporation Programmed(Personal) Data Processor - торговая марка корпорацииDigital Equipment для выпускающегося ею семействанедорогих миникомпьютеров.MULTICS - Multiplexed Information and Computing Service одна из первых операционных систем с разделениемвремени исполнения программ94Apple DOS - Apple Disk Operating System - Дисковаяоперационная системаCP/M - Control Program for Microprocessors-операционнаясистем CP/M - популярная в 1980-х гг.
ОС для 8-разрядныхПКMS/DOS - Microsoft Disk Operating System - дисковаяоперационная система для компьютеров на базеархитектуры х86 (80-е годы - сер. 90-х годов)Assignments1. Translate the sentences from the text into Russian inwriting paying attention to the underlined words andphrases:1. Eventually, all key elements of the operating systemsoftware are loaded, start-up programs are executed, theuser interface is provided, and the system is ready foruse.2.
Today PC operating systems are comparable insophistication and capability to those used inmainframes.3. They obviously need a network interface controller andsome low-level software to drive it, as well as programsto achieve remote login and remote file access.4.
Thus, some operating systems are designed to beconvenient, others to be efficient, and others somecombination of the two.2. Answer the following questions:1. What is the difference between application software andsystem software?2. Explain the term “booting the computer”.953. In multiprogramming a technique calledmemory is used. What does it mean?4. What is a kernel?5. Describe the evolution of the operating system.virtual3. Translate into English:BIOS - первый шаг к созданию операционныхсистем.Первые ЭВМ (40-е годы ХХ века) в силу спецификиприменения(решениеединственнойзадачи)неиспользовали никакой операционной системы. Вскоре ЭВМначали успешно применять для решения других задач:анализ текстов и решение сложных прикладных задач изобласти физики.
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